1. Field of the Present Invention
The present invention relates to a method of converting organic waste to usefull end product by aerobic thermophilic fermentation process within a short period of time by using porous material, which may contain cultivated thermophilic microorganisms, as a fermentation medium, and external heat to achieve thermophilic temperature.
2. Description of Related Arts
Large quantities of organic waste are produced from families and processing plants in the city and urban area everyday. Animal wastes are the largest source of both nitrogen and phosphorus pollution. It accounts for about more than half of total nitrogen loading and two-third of total phosphorous loading to the issue. As the production of livestock and poultry largely concentrated in certain regions and states, the air and water pollution problems have come along from the generation of manure. The most common methods include disposing organic waste to sanitary landfill and processing in composting facilities.
Due to the limited landfill spaces and the public resistance to new landfill, an alternative solution of waste problem becomes an urgent issue nowadays.
In fact, all organic wastes contain ambient nutrients for agriculture and animal feed industry. Composting manure and food residuals can reduce the biological activity and moisture. The organic matter in compost improves soil nutrient-holding and water-retaining capabilities which reduce fertilizer requirements and erosion while enhancing soil tilled. It also reduces odor and fly problem. While there are many benefits for composting, there is no promise to solve all manure and waste management problems. A composting operation takes time and money to manage and maintain. It will take extra land and mature time, usually from 3 weeks to 2 months. Compost windrows and storage facilities for raw materials will occupy large land and building space. With larger operations, composting becomes a very capital- and labor-intensive task. The most serious problem that can be developed with composting is run-off and odor pollution. If the compost pile contains too much nitrogen, ammonia odor becomes intolerable to neighbors. The excessive runoff and leachate are other potential pollution problems.
It is well known by using thermophilic microorganisms naturally present in the waste to dispose organic waste material. Pathogen and other contaminants in waste material are destroyed as the temperature raised up to 80.degree. C. This method increases safety usage of the end products.
Several technologies have taught the using of thermophilic fermentation method to process organic wastes. For example, in U.S. Pat. Nos. 5,810,903 (1998), 5,702,499 (1997), 4,292,328 (1981), 4,132,638 (1979), 3,864,247 (1975), 3,838,198 (1974), 3,745,113 (1973), 3,462,275 (1969).
Some other technologies introduce the using of porous material to immobilize and proliferate microorganisms for wastewater treatment or other applications. For example, U.S. Pat. Nos. 5,863,789 (1999), 5,595,893 (1997), 5,240,611 (1993), 5,185,255 (1993), 5,180,495 (1993).
U.S. Pat. No. 5,810,903, issued to Branconnier et al, suggests a process for thermophilic aerobic fermentation organic waste. The fermentation process utilizes thermophilic microorganisms initiated over a period of time from 2 to 6 days. Then, the process that completely converts the organic waste to end products requires about 24 to 48 hours. This whole procedure requires complicated operation and equipment.
U.S. Pat. No. 5,702,499, issued to Timmenga, discloses a waste conversion by liquid thermophilic aerobic digestion. This method needs to carefully monitor and control the thermophilic digestion process for the determination of the length of the process. The `end point` varies greatly with quality of the material processed and must be identified for each batch.
U.S. Pat. No. 4,292,328, issued to Coulthard et al, teaches a thermophilic aerobic digestion process for producing animal nutrients and other digested products. This method introduces air into the agitated mixture to bring temperature to at least 55.degree. C. without using external heat and cause thermophilic microbial digestion of waste material. The complete process needs at least 4 days to complete.
U.S. Pat. No. 4,132,638, issued to Carlsson, suggests an aerobic thermophilic degradation with enzyme addition. Enzyme is added to promote degradation prior to preheated material. The degradation treatment takes 10 days to complete. The treatment has three critical factors needed to take care before process: particle size, dry matter, and pH must be satisfied.
U.S. Pat. No. 3,864,247, issued to Fuchs, discloses a biological decomposition of organic material by thermophilic microorganisms. This method does not use heat addition for thermophilic microbial activity. The process time needs 5 days.
U.S. Pat. 3,838,198, issued to Bellamy et al, introduces a conditioning raw waste input for digestion by thermophilic aerobic microorganisms. This method preheats material between 75.degree. C. to 85.degree. C. for a period of about 1 to 2 days. It does not mention the length of process time.
U.S. Pat. No. 3,745,113, issued to Fuchs et al, suggests a biological decomposition of organic material. This treatment brings heat to at least 42.degree. C. by thermophilic microbial activity without external heat addition. It takes 6 to 10 days to process.
U.S. Pat. No. 3,462,275, issued to Bellamy, teaches a waste conversion process and product. The treatment utilizes a liquid medium with a thermophilic microorganism to convert waste.
U.S. Pat. No. 5,863,789, issued to Komatsu et al, discloses a microorganism-holding carrier and method for remediation of soil employing the carrier. This application uses hydrophilic polymer for holding microorganisms to manifest a biological action of microorganisms to remedy soil.
U.S. Pat. No. 5,595,893, issued to Pometto, III et al, suggests an immobilizing of microorganisms on a support made of synthetic polymer and plant material. This method uses synthetic polymer to immobilize microorganism to form a biofilm reaction for use in continuous formation in waste treatment system to remove contaminants and to reduce biochemical oxygen demand levels.
U.S. Pat. No. 5,240,611, issued to Burton, discloses an organic waste recycling system and method. This method utilizes porous material to treat liquid-borne organic waste.
U.S. Pat. No. 5,185,255, issued to Endo et al, suggests a cell culture method which uses porous material to proliferate microorganisms.
U.S. Pat. No. 5,180,495, issued to Thuer et al, suggests a water purification process which uses porous material populated by one or more microorganisms to purify water.
A common disadvantage of the above mentioned conventional arts is either the procedure is too complicated or needs more than 3 days to finish a complete process cycle or for water treatment purpose.
Although every patent presents a thermophilic method to process organic waste or uses porous material to carry microorganisms, none of them are designed to use porous material, which may contain cultivated thermophilic microorganisms, as a fermentation medium to decompose waste matters within 24 hours. Neither of these inventions offers an easy and simple operation procedure and low capital investment on equipment.